Radio frequency amplifier



June 2, 1942,. w 'KUMMERER 2,285,164 RADIO FRE UENCY AMPLIFIER Filed Aug. 24, 1940 INVENTOR W/LHELM KUMMERER 0 l "g f Vk M ATTORNEY dex (R) stands mu eums, 1942 UNITED STATES PATENT orrlcs namo 3:322 I Wilhelm Kummerer, Berlin, Germaimassignor to Telefunken Gesellscliaft tiir Dralitloae .lele-' graplile m. b. IL, Berlin, Germany, a corporaiion of Germany Application sum 24, 1940, Serial No. 354,031

' In Germanyllarcli ;25, 1989 5 Claims.

The present invention is concerned with a method adapted to improve the emciency, that is,

to raise the power output. of tubes of the class A and B carrier-wave amplifying type, of the kind employed, for instance, in input-stage-modulated transmitters as power amplifiers, for reasons of their rectilinearity.

It is an object of my invention to increase the a power output in an ampliiier.. This is secured phased so as tobroaden and flatten or otherwise.

re-shape the fundamental waves of plate voltage.

Referring to Fig. 2, U is the plate potential and I the plate current. The index 0 represents D. C. voltage or current, and the index '10 refers to alternating voltage or current. The fundamental wave and the harmonics are designated by (I), (111) etc. as raised indices, while a similar infor resultant potential or current.

I'he iact that the efliciency may be improved by the use of ripple-shaped alternating plate potential as such has been known in the prior art ponent of the higher" odd harmonics, a fact demonstrated not only by the'Fourier analysis,

but which is demonstrable in a purely graphicv form by assuming afull sine-wave plot to result from, or to be the sum total of the Fourier components of two lines representing half waves. Members of odd order in this case would become added and would not vanish in line with what is required. Hence, the requisite distortion of the pfate alternating potential can not be obtained by resonance resistance for the third or for higher odd harmonics as is true of the known circuit scheme. In fact, according to the'invention, the required voltage components are separately produced and induced into the plate lead. For instance. in the case of the third harmonic this is illustrated in Fig'.. 1. Inasmuch as the plate current contains no components of these frequencies, the harmonic voltage sources are neither fed with energynor is energy derived as to be negligible.

the transmitter tube 4.

for a long while. According to the disclosures of 'Rukop, Barkhausen, and Round (see the book. by Zenneck-Rukop, entitled Drahtlose Telegthe input power r l r and thus the theoretically maximum emciency =fi= =g Now, contradistlnct to this scheme I provide Referring to Fig. l, l denotes theinput amplifler tube, the grid circuit of which is fed with the RF energy at the terminals 2. The plate circuit of this tube is tuned to the fundamental wave I and is associated with the controlgrid of The modulation frequency NFis fed to the input stage I by way of the transformer 5. Also associated with terminal 2 is a frequency multiplier stage V in which, for instance, the third harmonic is of the fundamental wave "is generated. This harmonic may also be modulated by AF. The third harmonic is induced in the plate lead of tube 4.

For practical purposes, it sufllces to introduce only the third harmonic, though also higher odd harmonics could be added. "Fig. 2 shows the form of the resultant voltage curve UN in this case, that is, first (curve I) for the voltage of the third harmonic a value which at the time of maximum grid po tential, and thus also current output, results in the same residual potential as the purely ripv pie-shaped wave The output power is the input power and thus the efficiency of the tube N B 4 U U; with the addition of third harmonics equal in amount to curve III may be made just 4/K times greater than without this step, with the additional result that the tube power which is delivered is madeto rise to a like extent. The tube efliciency, in the presence of the residual potential UR required for a given working stage assumes this simple form y 1 l l In the case of an ideal tube free from residual voltage, therefore, the theoretically highest efficiency of 100 percent would be obtained (in contrast to 81 percent in the case above mentioned).

For a working voltage of 12 kv. and a residual voltage of around 1200 v. (which corresponds to the conditions of the 200 kw. tube model RS 301) high-frequency amplifier, means for feeding a carrier wave to said amplifier, frequency mul- 2,2s5,1e4 I y tiplier means for impressing on'the output circult of said amplifier an odd harmonic component of said carrier wave, and means for so controlling the amplitude and phase of said odd harmonic component as to broaden and flatten the fundamental wave peaks derived from said amplifier.

2. A circuit arrangement comprising a high frequency amplifier having at least one stage the output circuit of which includes resonant elements tuned to a fundamental frequency and to an odd harmonic frequency, a frequency multiplier having an output circuit coupled to the inductance of said harmonically tuned resonant element, and energy diversion means connected to the'source of inputv energy for said amplifier and arranged to feed input energy to said frequency multiplier.

3. A circuit arrangement according to claim 2 wherein said harmonically tuned resonant element is tuned to the third harmonic of said fundamental frequency.

4. A circuit arrangement according to claim 2 wherein means are provided for combining the output energies from said amplifier and said frea utilization circuit coupled to that inductivev element which resonates at said fundamental frequency, and arranged to receive energy components both from said amplifier and from said frequency multiplier.

WILHELM KUMMERER. 

